There has been known a technique where, in order to execute software on an environment different from a specific environment on which the software is developed to be executed, software called “emulator” is executed so that the software developed for the specific environment is executed on the emulator. This technique may be called “emulation”.
A general processor includes a Memory Management Unit (MMU), so that the MMU uses an address conversion table to convert a virtual address that a host OS recognizes into a physical address.
Further, the emulator that executes the emulation of the MMU of the processor converts a physical address that a guest OS recognizes into a virtual address that the host OS recognizes. By doing this, a guest program running on the guest OS may access a memory via the guest OS, the emulator, and the MMU.
In relation to this, in a multimode architecture computer system, there has been known a method of switching temporary processor mode contexts between first and second modes. In this method, the MMU of the computer system is first deactivated. Then, the mode control register is changed to set (change) the context bit from the first mode to the second mode. Then, a new page table related to the second mode is read, and the MMU is activated again.
Reference may be made to Japanese Laid-open Patent Publication No. 2006-018819.